Surgical site infections (SSI) present a significant clinical problem in both spine and orthopaedic surgery. As well as being costly to the health care system, these infections interfere with wound healing and therefore prolong recovery time for patients. There is a need in the field for treatments to prevent surgical site infections at the local delivery site. The present invention addresses this need by providing a composite biomaterial that includes an antibacterial component for preventing surgical site infections.
Biomaterials, including various metals, polymers and ceramics, have been used as implant materials in the field of spine, orthopaedics and dentistry including fusion, trauma, fracture repair, reconstructive surgery and alveolar ridge reconstruction, for over a century due to their biocompatibility and physical properties. Among these biomaterials, porous calcium phosphate-based bone grafts are known in the art for use in filling bony voids or gaps in the skeletal system. Examples of such bone grafts are described in, for example, U.S. Pat. No. 6,991,803; U.S. Pat. No. 6,521,246; and U.S. Pat. No. 6,383,519; No. incorporated herein. Vitoss® Bone Graft Substitute (Orthovita, Inc., Malvern Pa.) is one exemplary type of such bone grafts. Such porous calcium phosphate-based bone grafts have been further modified and improved to incorporate biocompatible materials such as, for example, polymers including collagen, to impart improved handling ability of the bone graft; and bioactive glasses, to further enhance the biological activity of the bone graft. Examples of such materials are described in, for example, U.S. Pat. No. 7,534,451; U.S. Pat. No. 7,531,004; U.S. Pat. No. 7,189,263 and U.S. Patent App. No. 20080187571, incorporated herein. Vitoss™ BA Bioactive Bone Graft Substitute (Orthovita, Inc., Malvern, Pa.) is one exemplary type of such a bone graft incorporating bioactive glass.
Bioactive (BA) glasses have been extensively studied for their bone bonding properties. The use of BA glass alone and in combination with other materials is generally described in U.S. Pat. No. 5,681,872; U.S. Pat. No. 5,914,356; and U.S. Pat. No. 6,987,136, each of which is assigned to the assignee of the present invention and is incorporated in this document by reference in its entirety.
The wound healing and bactericidal properties of BA glasses have also been reported, particularly BA glasses of certain particle size ranges. U.S. Pat. No. 6,756,060; U.S. Pat. No. 6,428,800 and U.S. Pat. No. 5,834,008 describe wound and burn dressings comprising BA glass. However, the BA glass is generally combined with topical antibiotic and incorporated into bandages.
Accordingly, there is a need in the art for implant materials and composites that induce bone formation and prevent surgical site infections. There is also a need in the art for a method of preparing a homogeneous bioactive antibacterial composite; and for methods of using bioactive antibacterial materials and composites in a variety of clinical applications including spine and orthopaedic procedures. The present invention fulfills these needs. It has been discovered that materials that include bioactive glass in a specific bimodal glass size distribution alone and incorporated within a collagen matrix along with calcium phosphate produce a bioactive antibacterial implant that successfully enhances bone growth and inhibits surgical site infection.